There is a need for a minimally obtrusive nasal mask and ventilation system that delivers mechanical ventilatory support or positive airway pressure, and which unencumbers the patient. There is a range of clinical syndromes that require ventilation therapy that would benefit from such a mask and system, such as respiratory insufficiency, airway or sleeping disorders, congestive heart failure, neuromuscular disease, and a range of situations that would be benefited, such as chronic, acute, emergency, mass casualty and pandemic situations.
Oxygen therapy is available with devices that do not encumber the patient; however, oxygen therapy is used for far less severe forms of clinical syndromes compared to ventilation therapy. For example, some nasal mask oxygen therapy systems have been developed for the purpose of delivering mixtures of air and oxygen by entraining air into the mask. These are not considered ventilation therapy or respiratory support, however, because they do not mechanically help in the work of breathing. Recently, a variant of oxygen therapy has been employed, known as high flow oxygen therapy (HFOT). In this case, the oxygen flow rate is increased beyond standard long term oxygen therapy (LTOT), for example, above 15 LPM. Because of the high flow rate, the oxygen must be humidified to prevent drying out the patient's airway. It has been reported that HFOT can slightly reduce the patient's absolute pleural pressure during spontaneous breathing, thus have a slight effect on work of breathing. These systems are inefficient in that they consume a significant quantity of oxygen, rendering them non-mobile systems and encumbering the patient.
Respiratory support and ventilation therapies exist that provide mechanical ventilation (MV) to the patient, and mechanically contribute to the work of breathing. MV therapies connect to the patient by intubating the patient with a cuffed or uncuffed tracheal tube, or a sealing face or nasal mask or sealing nasal cannula. While helpful in supporting the work of breathing, the patient interfaces used for MV are obtrusive and/or invasive to the user. These interfaces for MV do not facilitate mobility or activities of daily living, encumber a patient and are considered a drawback by many potential users. Non-invasive ventilation (NIV) exists which ventilates a patient with a face or nasal mask rather than requiring intubation, which can be an advantage in many situations. However, the patient cannot use their upper airway because the interface makes an external seal against the nose and/or mouth. Additionally, the system is not mobile. This combination of factors does not enable activities of daily living.
For treating obstructive sleep apnea (OSA), the gold standard ventilation therapy is continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), which is a variant to NIV in that the patient partially exhales through exhaust ports in the mask and back into large gas delivery tubing, rather than through an exhalation circuit as in MV. Continuous positive pressure applied by the ventilator to the patient by a nasal or face mask that seals against the nose or face prevents upper airway obstruction. While effective, this therapy has poor patient compliance because the patient interface is obtrusive to the patient and the patient unnaturally breathes through both a mask and gas delivery circuit.
In summary, existing therapies have several disadvantages. These disadvantages include, but are not limited to, not offering respiratory support or airway support in a manner that unencumbers the patient. Additionally, existing therapies: (1) are invasive and/or obtrusive such that they do not allow for mobility and activities of daily living; (2) do not allow the sensation of breathing from the ambient surroundings normally; and (3) are not provided in an easily portable system or a system that can be easily borne or worn by the patient.